Electric Motor Secrets

[Jetijs]

Ok, I have been busy today and the motor is finally finished
here's the startor ready for coil winding:


The coil winding process was the hardest part, because I did this with hands. The startor is heavy and with each turn of wire it became even heavier. I wound three strands of gauge 21 wire. There are about 250 turns ( I lost the count in the winding process which took me about 2 hours). Each strand has a resistance of 1.7 Ohms.



Now as for the reedswich. At first I tried to mount the reedswitch to the plexiglass holder horizontally, but that did not work well, the duty cycle was bad, about 70% on time and 30% off time at best.



Then I mounted the reedswitch to the holder vertically. This was a lot better, now I could easily adjust the timing as needed.



I had to make a second plywood base plate so I have a place to mount the reedswitch. Heres how it looks like:



And now pictures of the whole thing:





I have not adjusted the timings now, I just tested if the adjustment works. Now I need to solder the circuit. Peter I think you missed my previous question:

In the mean time can you answer a question? So If I wind my startor coil from several parallel strands of wire, what is the difference between pulsing each of the strand with its own transistor and pulsing them all together with only one transistor, provided that the transistor can handle enough current? When I experimented with SSG circuits, I noticed, that I can get more RPM with two power coils if I pulse them with two transistors, each transistor for each coil. But when I used only one transistor and pulsed the both coils in parallel, I got only a little increase of RPM. Why is this so?
Thanks

Thanks,
Jetijs

[bobo36us]

Work of art!

Hey Jetijs, that is definately a thing of beauty! We can't wait to see
your results after you get your timing perfected!

I was a little surprised however to see Peter say that you will "not be able to see high torque production" with your air gap at .3mm

I am sure you are correct Peter, but what kind of power loss is there with
a .3mm versus say a .1mm, and how the heck would you ever get a .1mm
anyway???? Isn't that thinner than paper????

Even with some state of the art machining, what about the "slop" in your
nuts and bolts and bearings?

Keep up the good work!

Bob

[nali2001]

Motor

Hi there Bob an'all.
Well I have found that some (new) ball bearing have radial play (super very minor though) and also axial play (not at all that minor) So just to be safe I used roller bearings since you can adjust them.
A sheet of paper is actually more in the range of 0.05 to 0.08mm At the moment my system uses 0.07mm and I have seen that it is very possible to go even beyond that, IF your stator is actually that exact also. I use a deviation from the ‘original’ attraction motor design. Since I use normal induction motor stators and these are of course professionally made and so ‘very’ precise. The rotor is machined 0.5mm to big and when it is finished I machine the last outer diameter of the rotor and axle section for the bearings in one pass. (Without taking it out of the chuck) So it is maximum/high precision.

Finally finished wiring the stator. Had tons of problems with the insulation for the coils. Like ten times somewhere in the wrapping process I discovered a short to the core. Finally settled for cloth-epoxy insulation since multiple layers of tape does not cut it. Not much room in there also.The wiring is low inductance. Each coil (my stator has two) is 1.1 ohm 0.8mm wire. I’m lucky that this stator design must have very short pulses since I=v/r so my thing will be eating like 10 amps or 20amps at 24v on full on. Funny if you think about it. The rotor has 8 fingers and the stator has 16 so that means in each revolution there are 128 attraction ‘places’.

Well here are some pictures. The wheel at the back is for the opto trigger stuff. (Still had that wheel from another machine)

Regards,
Steven

[Peter Lindemann]

Jetijs and Steven

Jetijs,

Without seeing your exact schematic circuit, including the output section, I don't know why you are seeing the behavior you report. I know that John and I ran numerous tests with parallel coils and found that parallel coils triggered by a single transistor tend to discharge INTO each other rather than out through the output section. This slows down the field collapse and reduces the amount of recoverable energy.

Steven,

Your motor is looking very good. The torque should be excellent for input power. The recoverable energy will depend on your switch timing and recovery circuits. I know I speak for many people on this forum who are very interested in your test results. We all look forward to your motor performing extremely well.

Peter

[lighty]

I know that John and I ran numerous tests with parallel coils and found that parallel coils triggered by a single transistor tend to discharge INTO each other rather than out through the output section. This slows down the field collapse and reduces the amount of recoverable energy.

In other words Litz wire should be avoided for winding the energizer coil?

[Jetijs]

Steven,
those are some awesome pictures. Thank you for sharing
I see that you have a fan attached to the shaft, is this for cooling purposes because of the eddy currents? Would it not be better to use thin plates of silicon steel bolted together in one large rotor piece? I know that this stuff is hard to get, but shouldn't it in theory reduce the heat?
Thanks

[Jetijs]

Ok Peter,
I did some test runs on my motor. The circuit is exactly like in your youtube videos except that I used the 2N3055 transistor and the nominals of the resistors are 200 Ohms (R1) and 196 Ohms (R2). I used only one of the three strands. At first I set the voltage of my variac to 30V and hooked up an analog amp meter. I shorted the output on the first test and got 1.1A current draw and 655 RPM. Next I attached 12v light bulb to the output, now the current draw reduced to exactly 0.4A and the RPM increased to 920. This time I noticed the neon bulb doing some flashes occasionally. It flashed a little bit mode when the motor was starting to gain speed, at the full speed the neon flashed only very few times and dimly. I suppose this is because the bulb can not take all of the charge and what is left goes to the neon. But the light bulb was shining very brightly. For the last test I attached a discharged 1.3Ah lead acid battery to the output. This time I did not see any decrease in current draw, but the RPM went up a little bit to 956. Also the neon bulb was not flashing at all, that means the battery absorbs the recycled energy very well. When I started this last test, the battery voltage increased from 11.60 to 12.24 in some seconds, then it settled down and continued to increase slower. So the results:

Test 1. Voltage 30V Current draw 1.1A RPM 655
Test 2. Voltage 30V Current draw 0.4A RPM 920
Test 3. Voltage 30V Current draw 0.4A RPM 956

And all this with only one strand of gauge 21 wire
Will do some more testing, but I must change the bearings first, because there is some friction in them and that makes the motor noisy and reduce the performance.

[Jan H]

Jetijs,
sounds awesome! can't wait to see a movie of that thing spinning! You really didn't cut any corners. very professional

Bobo,
About the air gap, you are right when you say its hard to get it very small. But the way I imagine it is like having two magnets attract eachother, when they get really close, lets say >1mm the force of them pulling together increases exponentially. I THINK that is what makes the need for a small air gap.

[Peter Lindemann]

You get the GOLD STAR!!!

Ok Peter,
I did some test runs on my motor. The circuit is exactly like in your youtube videos except that I used the 2N3055 transistor and the nominals of the resistors are 200 Ohms (R1) and 196 Ohms (R2). I used only one of the three strands. At first I set the voltage of my variac to 30V and hooked up an analog amp meter. I shorted the output on the first test and got 1.1A current draw and 655 RPM. Next I attached 12v light bulb to the output, now the current draw reduced to exactly 0.4A and the RPM increased to 920. This time I noticed the neon bulb doing some flashes occasionally. It flashed a little bit mode when the motor was starting to gain speed, at the full speed the neon flashed only very few times and dimly. I suppose this is because the bulb can not take all of the charge and what is left goes to the neon. But the light bulb was shining very brightly. For the last test I attached a discharged 1.3Ah lead acid battery to the output. This time I did not see any decrease in current draw, but the RPM went up a little bit to 956. Also the neon bulb was not flashing at all, that means the battery absorbs the recycled energy very well. When I started this last test, the battery voltage increased from 11.60 to 12.24 in some seconds, then it settled down and continued to increase slower. So the results:

Test 1. Voltage 30V Current draw 1.1A RPM 655
Test 2. Voltage 30V Current draw 0.4A RPM 920
Test 3. Voltage 30V Current draw 0.4A RPM 956

And all this with only one strand of gauge 21 wire
Will do some more testing, but I must change the bearings first, because there is some friction in them and that makes the motor noisy and reduce the performance.

Jetijs,

Very, Very Good. Solve your bearing issues and resume your tests. As you add all three strands to the power side (each with their own transistor) your input should triple to about 1.2A. The output to the 12 volt battery will be over 2.0A, so you may want a larger battery to charge than your little 1.2AH one.

Also, you will be able to trigger all three transistors from the single magnetic reed, but you will need to balance the branches to each transistor base.

Keep up the great work!

Peter

[Jetijs]

I uploaded a short video on youtube, you can watch it here:
YouTube - Lindemann attraction motor

Peter, I don't understand this balancing of the branches. Can you please explain what you mean?
Thank you

[lighty]

@Jetijs

I noticed a strange vibrating sound when your motor is in operation. Something is not balanced or not centered correctly or with low enough tolerance.

Did you consider using another base plate and another bearing so that you can have a 2 point shaft support? You can then use self-centering axial-radial bearing at one side to compensate for eventual lateral movements. I have had experience building powerful motor from scratch and one point support of shaft is simply too unreliable for the forces involved. Especially with pulse motors.

Nevertheless - a GREAT work pal!

[Jan H]

@Jetijs

I noticed a strange vibrating sound when your motor is in operation. Something is not balanced or not centered correctly or with low enough tolerance.

Did you consider using another base plate and another bearing so that you can have a 2 point shaft support? You can then use self-centering axial-radial bearing at one side to compensate for eventual lateral movements. I have had experience building powerful motor from scratch and one point support of shaft is simply too unreliable for the forces involved. Especially with pulse motors.

Nevertheless - a GREAT work pal!

if you check the commutator side you can see that he does have two bearings on there, still I think you may be right adding another bearing, but i would place it on top, where there is none at the moment. Or is that what you actually meant?
Also I doubt whether all the noise is coming from the bearings. Tweaking the timing a little bit might also decrease noise.

[lighty]

if you check the commutator side you can see that he does have two bearings on there, still I think you may be right adding another bearing, but i would place it on top, where there is none at the moment. Or is that what you actually meant?

Yup, that's exactly what I was suggesting. To put another bearing on the other end of the shaft (on the top).

[Jetijs]

That noise is coming from the bearings, I am sure about this, because even when I rotate the rotor with my hand, there is that noise. The comutator wheel is a little bit off center, but that is not the cause of that noise, because the noise is there even without the comutator. I will replace these bearings and if that wont work I will consider using those self centering ones
Thanks.

[nali2001]

Hi there Jetijs,
Nice going man great build!

How do you get your DC? I mean a variac is obviously ac and even with a full wave bridge and cap it will not really be clean dc.

On your questions:
Yes the fan will be there for the possible(likely) heat development since every component has losses and also the windings develope heat. And since my system is enclosed it has no real open air cooling like yours so just to be sure I used the fan that forces air through the holes in the end caps.
Laminates are obviously better but since this is a small baby unit and a somewhat experimental approach I play it safe and used the simple solid steel.

Regards,
Steven